Ciena unveils, deploys new submarine network modulation format

Ciena Corp. (NYSE: CIEN) has announced a pair of submarine network upgrade wins that leverage a newly available modulation format. Both the Trans Pacific Express (TPE) and Japan-U.S. Cable Network undersea cable systems have embarked on upgrade programs that will use Ciena's 8D-2QAM modulation scheme.

The new scheme -- eight-dimensional 2QAM -- features two bits per symbol, which gives it a spectral efficiency similar to BPSK, according to a Ciena source. The eight-dimensional aspect of the format provides greater noise immunity and less nonlinear interference than four-dimensional modulation formats such as DP-QPSK, the source added. The company's WaveLogic 3 coherent transmission processor will power such transmissions.

In the case of the Japan-U.S. Cable Network deployment, the system's upgrade also will use 16QAM modulation to support 200-Gbps transmission rates on the system's shortest links, after a trial of the technology last year (see "Ciena tests 200G via 16-QAM with Japan-U.S. Cable Network"). The upgrade also will achieve a 60% or more increase in the design capacity of the longest transpacific segment. Overall, the submarine cable network spans close to 22,000 km.

Meanwhile, the TPE upgrade will more than triple the original capacity of the 17,968-km international submarine cable system to multi-terabit levels. As is the case with the Japan-U.S. upgrade, the TPE project will leverage elements of Ciena's GeoMesh portfolio, including the Ciena 6500 packet-optical transport system with flexible-grid capabilities.

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